Background of Ferulic Acid
Ferulic acid (FA) is a widely existing phenolic acid compound. In 1866, German Hlasweta.H first isolated FA from Ferula foetida regei, hence the name. The chemical formula of FA is 4-hydroxy-3-methoxy-2-phenylacrylic acid. Studies have shown that FA is widely present in fruits, vegetables, grains, beans and other types of plants. Studies have found that ferulic acid has unique and attractive physiological activities, such as antioxidant, antibacterial, anti-inflammatory, anti-aging, anti-cancer, etc.
Structural Characteristics of Ferulic Acid
According to different molecular structures, FA can be divided into cis and trans. Among them, cis-ferulic acid is a yellow oil, and trans-FA is a white or slightly yellow oblique square crystal. Studies have found that FA generally exists in a trans structure in nature. Therefore, the FA component in cosmetics mainly uses trans-structured FA. At present, FA has been widely used in industries such as medicine, food, and beauty and skin care products.
Application of Ferulic Acid Nanoparticles
Ferulic acid is generally absorbed in fat-soluble or water-soluble forms, and is easily absorbed by the small intestine of humans and mice. It exists in the body in the form of glycosides, glucosides and methyl esters, reaches all parts of the body through the blood, and is finally metabolized into compounds such as phenylpropionic acid and cinnamoylglycine, which are quickly excreted in the urine and do not accumulate in the body, but a small amount is excreted in the feces.
Figure 1. Biological functions and structure of ferulic acid. (Li D, et al.; 2021)
- The Skin Care Effects of Ferulic Acid
Ferulic acid can enter the human body through transdermal absorption, and the penetration coefficient is positively related to the concentration. This allows ferulic acid to exert its skin care effects by applying it on the skin. Ferulic acid's skin care effects are mainly reflected in antioxidant, sun protection, whitening, and anti-inflammatory.
1. Antioxidant Effect
Research has found that when the skin is stimulated by ultraviolet rays, skin cells will produce a large number of free radicals. The human body also produces a large number of free radicals during its own metabolism. These free radicals will attack normal cells and damage body tissues. If not removed in time, it will cause skin aging, sagging, pigmentation, spots, and roughness. Studies have shown that ferulic acid has strong antioxidant properties and can effectively remove a variety of free radicals, making it a natural free radical scavenger. In addition, ferulic acid can also remove excess reactive oxygen in the body and inhibit oxidative stress by inhibiting the production of lipid peroxide MDA.
2. Sunscreen effect
It is well known that ultraviolet rays are very harmful to human skin, so certain measures can be taken to offset the damage of ultraviolet rays to the skin. Studies have found that ferulic acid has a certain absorption effect on ultraviolet rays, and its maximum ultraviolet absorption peak is at 236nm and 322nm. Within this wavelength range, ferulic acid can absorb ultraviolet rays, thereby reducing skin damage. Therefore, ferulic acid can be used in conjunction with conventional sunscreens. This dual protective effect can minimize the damage of ultraviolet rays to the skin.
3. Whitening Effect
The primary cause of skin darkening is the production and cellular deposition of melanin. Tyrosinase is the key enzyme in this process. Studies have shown that the structure of ferulic acid is similar to the natural substrate of tyrosinase, so it inhibits the formation of melanin by competing with the substrate for the binding site of tyrosinase. Therefore, ferulic acid can reduce the production of melanin in skin cells, thereby achieving the effect of whitening and lightening spots.
Ferulic acid has excellent skin care effects, but it is very difficult to formulate ferulic acid into skin care products. When ferulic acid exists in the form of solid powder, it has very good stability. However, in aqueous solution, it is easily affected by light, pH value, and temperature and decomposes and loses its activity. Therefore, liposomal ferulic acid made by encapsulating ferulic acid with liposomes not only improves the stability of ferulic acid, but also improves the absorption ability of ferulic acid to penetrate the skin and cells.
- Ferulic Acid Improves Immunity
Studies have found that ferulic acid can significantly increase the weight of mouse spleen and thymus, improve the phagocytosis function of mouse peritoneal macrophages, and promote the proliferation of mouse B cells and ConA-induced mouse spleen lymphocytes. This shows that ferulic acid has an effect on mouse spleen and thymus. Both humoral immunity and cellular immunity have strong promoting effects.
Activation of complement attracts neutrophils to gather locally and generates reactive oxygen species, which is an important cause of tissue and organ damage. Ferulic acid can prevent neutrophils from gathering locally caused by activated complement and can significantly inhibit neutral lobulated nuclei. Cells undergo a respiratory burst to produce reactive oxygen species when stimulated by zymosan.
- Antibacterial and Anti-Inflammatory Effects of Ferulic Acid
Studies have found that ferulic acid has an inhibitory effect on some bacteria and viruses. The reason is that ferulic acid inhibits the activity of enzymes that are closely related to the survival of these microorganisms. For example, ferulic acid can inhibit N-acetyltransferase, which is closely related to the survival of bacteria. The inhibition of this enzyme will lead to the death of bacteria and achieve the purpose of antibacterial. In addition, ferulic acid can also inhibit the activity of xanthine oxidase associated with certain inflammatory diseases, thereby showing an anti-inflammatory effect. Therefore, ferulic acid has a broad spectrum of antibacterial and anti-inflammatory effects.
Reference
- Li D, et al.; Ferulic acid: A review of its pharmacology, pharmacokinetics and derivatives. Life Sci. 2021, 284:119921.
